feat(forms): introduce min and max validators (#15813)

PR Close #15813

packages/forms/src/directives/validators.ts

@@ -57,6 +57,7 @@ export const CHECKBOX_REQUIRED_VALIDATOR: Provider = {
   multi: true
 };
 
+
 /**
  * A Directive that adds the `required` validator to any controls marked with the
  * `required` attribute, via the {@link NG_VALIDATORS} binding.
@@ -94,6 +95,84 @@ export class RequiredValidator implements Validator {
   registerOnValidatorChange(fn: () => void): void { this._onChange = fn; }
 }
 
+export const MIN_VALIDATOR: Provider = {
+  provide: NG_VALIDATORS,
+  useExisting: forwardRef(() => MinValidator),
+  multi: true
+};
+
+/**
+ * A directive which installs the {@link MinValidator} for any `formControlName`,
+ * `formControl`, or control with `ngModel` that also has a `min` attribute.
+ *
+ * @experimental
+ */
+@Directive({
+  selector: '[min][formControlName],[min][formControl],[min][ngModel]',
+  providers: [MIN_VALIDATOR],
+  host: {'[attr.min]': 'min ? min : null'}
+})
+export class MinValidator implements Validator,
+    OnChanges {
+  private _validator: ValidatorFn;
+  private _onChange: () => void;
+
+  @Input() min: string;
+
+  ngOnChanges(changes: SimpleChanges): void {
+    if ('min' in changes) {
+      this._createValidator();
+      if (this._onChange) this._onChange();
+    }
+  }
+
+  validate(c: AbstractControl): ValidationErrors|null { return this._validator(c); }
+
+  registerOnValidatorChange(fn: () => void): void { this._onChange = fn; }
+
+  private _createValidator(): void { this._validator = Validators.min(parseInt(this.min, 10)); }
+}
+
+
+export const MAX_VALIDATOR: Provider = {
+  provide: NG_VALIDATORS,
+  useExisting: forwardRef(() => MaxValidator),
+  multi: true
+};
+
+/**
+ * A directive which installs the {@link MaxValidator} for any `formControlName`,
+ * `formControl`, or control with `ngModel` that also has a `min` attribute.
+ *
+ * @experimental
+ */
+@Directive({
+  selector: '[max][formControlName],[max][formControl],[max][ngModel]',
+  providers: [MAX_VALIDATOR],
+  host: {'[attr.max]': 'max ? max : null'}
+})
+export class MaxValidator implements Validator,
+    OnChanges {
+  private _validator: ValidatorFn;
+  private _onChange: () => void;
+
+  @Input() max: string;
+
+  ngOnChanges(changes: SimpleChanges): void {
+    if ('max' in changes) {
+      this._createValidator();
+      if (this._onChange) this._onChange();
+    }
+  }
+
+  validate(c: AbstractControl): ValidationErrors|null { return this._validator(c); }
+
+  registerOnValidatorChange(fn: () => void): void { this._onChange = fn; }
+
+  private _createValidator(): void { this._validator = Validators.max(parseInt(this.max, 10)); }
+}
+
+
 /**
  * A Directive that adds the `required` validator to checkbox controls marked with the
  * `required` attribute, via the {@link NG_VALIDATORS} binding.